Table 2

Deorphanized taste receptors

Receptors


Ligands

Human

Mouse


Sugars, sweeteners, D-amino acids1

hT1R2 + hT1R3

mT1R2 + mT1R3

Umami stimuli and L-amino acids

hT1R1 + hT1R3

mT1R1 + mT1R3

Beta-glucopyranosides

hT2R16

PROP

hT2R42

mT2R82

Structurally diverse set of bitter stimuli

hT2R14

Strychnine

hT2R10

Saccharin, acesulfame K

hT2R44, hT2R43

PTC

hT2R38

Denatonium

hT2R4, hT2R44

mT2R8

Cycloheximide

mT2R5


The ligand specificities have been determined predominantly by in vitro studies, but also through the use of knock-out or transgenic mice, as well as other approaches examining allelic variance. The sweet and amino acid receptors have broad ligand specificity. The T1R2 + T1R3 heterodimer responds to a broad array of sweet-tasting stimuli in both human and mouse [85–87]. T1R1 + T1R3 responds to umami stimuli in humans and to a wider range of stimuli including a variety of L-amino acids in mice [86, 87]. A T1R3 homodimer may respond to sugars at higher concentrations [88, 90]. In contrast, most of the bitter receptors have narrow ligand specificities [111, 112, 125, 250, 251]. However, hT2R14 has been shown to respond to a broad group of bitter compounds, including plant neurotoxins [252].

1Excepting D-glutamate and D-aspartate.

2Only high concentrations of PROP were found to activate this receptor in vitro.

Boughter and Bachmanov BMC Neuroscience 2007 8(Suppl 3):S3   doi:10.1186/1471-2202-8-S3-S3

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